nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-components/src/main/java/org/apache/nifi/util/ReflectionUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.nifi.util;

import org.apache.nifi.logging.ComponentLog;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;

public class ReflectionUtils {

    private final static Logger LOG = LoggerFactory.getLogger(ReflectionUtils.class);
    private static Map<Class<?>, Map<Annotations, List<Method>>> annotationCache = new WeakHashMap<>();

    /**
     * Invokes all methods on the given instance that have been annotated with the given Annotation. If the signature of the method that is defined in <code>instance</code> uses 1 or more parameters,
     * those parameters must be specified by the <code>args</code> parameter. However, if more arguments are supplied by the <code>args</code> parameter than needed, the extra arguments will be
     * ignored.
     *
     * @param annotation annotation
     * @param instance instance
     * @param args args
     * @throws InvocationTargetException ex
     * @throws IllegalArgumentException ex
     * @throws IllegalAccessException ex
     */
    public static void invokeMethodsWithAnnotation(
            final Class<? extends Annotation> annotation, final Object instance, final Object... args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
        invokeMethodsWithAnnotations(annotation, null, instance, args);
    }

    /**
     * Invokes all methods on the given instance that have been annotated with the given preferredAnnotation and if no such method exists will invoke all methods on the given instance that have been
     * annotated with the given alternateAnnotation, if any exists. If the signature of the method that is defined in <code>instance</code> uses 1 or more parameters, those parameters must be
     * specified by the <code>args</code> parameter. However, if more arguments are supplied by the <code>args</code> parameter than needed, the extra arguments will be ignored.
     *
     * @param preferredAnnotation preferred
     * @param alternateAnnotation alternate
     * @param instance instance
     * @param args args
     * @throws InvocationTargetException ex
     * @throws IllegalArgumentException ex
     * @throws IllegalAccessException ex
     */
    @SuppressWarnings("unchecked")
    public static void invokeMethodsWithAnnotations(final Class<? extends Annotation> preferredAnnotation,
            final Class<? extends Annotation> alternateAnnotation, final Object instance, final Object... args)
                    throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {

        Class<? extends Annotation>[] annotationArray = (Class<? extends Annotation>[]) (alternateAnnotation != null
                ? new Class<?>[] { preferredAnnotation, alternateAnnotation } : new Class<?>[] { preferredAnnotation });
        invokeMethodsWithAnnotations(false, null, instance, annotationArray, args);
    }

    /**
     * Invokes all methods on the given instance that have been annotated with the given Annotation. If the signature of the method that is defined in <code>instance</code> uses 1 or more parameters,
     * those parameters must be specified by the <code>args</code> parameter. However, if more arguments are supplied by the <code>args</code> parameter than needed, the extra arguments will be
     * ignored.
     *
     * @param annotation annotation
     * @param instance instance
     * @param args args
     * @return <code>true</code> if all appropriate methods were invoked and returned without throwing an Exception, <code>false</code> if one of the methods threw an Exception or could not be
     * invoked; if <code>false</code> is returned, an error will have been logged.
     */
    public static boolean quietlyInvokeMethodsWithAnnotation(final Class<? extends Annotation> annotation, final Object instance, final Object... args) {
        return quietlyInvokeMethodsWithAnnotations(annotation, null, instance, null, args);
    }

    /**
     * Invokes all methods on the given instance that have been annotated with the given Annotation. If the signature of the method that is defined in <code>instance</code> uses 1 or more parameters,
     * those parameters must be specified by the <code>args</code> parameter. However, if more arguments are supplied by the <code>args</code> parameter than needed, the extra arguments will be
     * ignored.
     *
     * @param annotation annotation
     * @param instance instance
     * @param logger logger
     * @param args args
     * @return <code>true</code> if all appropriate methods were invoked and returned without throwing an Exception, <code>false</code> if one of the methods threw an Exception or could not be
     * invoked; if <code>false</code> is returned, an error will have been logged.
     */
    public static boolean quietlyInvokeMethodsWithAnnotation(final Class<? extends Annotation> annotation,
            final Object instance, final ComponentLog logger, final Object... args) {
        return quietlyInvokeMethodsWithAnnotations(annotation, null, instance, logger, args);
    }

    /**
     * Invokes all methods on the given instance that have been annotated with the given preferredAnnotation and if no such method exists will invoke all methods on the given instance that have been
     * annotated with the given alternateAnnotation, if any exists. If the signature of the method that is defined in <code>instance</code> uses 1 or more parameters, those parameters must be
     * specified by the <code>args</code> parameter. However, if more arguments are supplied by the <code>args</code> parameter than needed, the extra arguments will be ignored.
     *
     * @param preferredAnnotation preferred
     * @param alternateAnnotation alternate
     * @param instance instance
     * @param args args
     * @return <code>true</code> if all appropriate methods were invoked and returned without throwing an Exception, <code>false</code> if one of the methods threw an Exception or could not be
     * invoked; if <code>false</code> is returned, an error will have been logged.
     */
    public static boolean quietlyInvokeMethodsWithAnnotations(final Class<? extends Annotation> preferredAnnotation, final Class<? extends Annotation> alternateAnnotation,
            final Object instance, final Object... args) {
        return quietlyInvokeMethodsWithAnnotations(preferredAnnotation, alternateAnnotation, instance, null, args);
    }

    private static boolean invokeMethodsWithAnnotations(boolean quietly, ComponentLog logger, Object instance, Class<? extends Annotation>[] annotations, Object... args)
            throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {

        return invokeMethodsWithAnnotations(quietly, logger, instance, instance.getClass(), annotations, args);
    }

    private static boolean invokeMethodsWithAnnotations(boolean quietly, ComponentLog logger, Object instance, Class<?> clazz, Class<? extends Annotation>[] annotations, Object... args)
            throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {

        boolean isSuccess = true;
        final List<Method> methods = findMethodsWithAnnotations(clazz, annotations);
        for (final Method method : methods) {
            Object[] modifiedArgs = buildUpdatedArgumentsList(quietly, method, annotations, logger, args);
            if (modifiedArgs != null) {
                try {
                    method.invoke(instance, modifiedArgs);
                } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
                    isSuccess = false;
                    if (quietly) {
                        final Throwable cause = (e instanceof InvocationTargetException) ? e.getCause() : e;
                        logErrorMessage("Failed while invoking annotated method '" + method + "' with arguments '"
                            + Arrays.asList(modifiedArgs) + "'.", logger, cause);
                    } else {
                        throw e;
                    }
                }
            }
        }

        return isSuccess;
    }

    private static List<Method> findMethodsWithAnnotations(final Class<?> clazz, final Class<? extends Annotation>[] annotationClasses) {
        // We use a cache here to store a mapping of Class & Annotation[] to those methods that contain the annotation.
        // This is done because discovering this using Reflection is fairly expensive (can take up to tens of milliseconds on laptop).
        // While this may not seem like much time, consider deleting a Process Group with thousands of Processors or instantiating
        // a Template with thousands of Processors. This can add up to several seconds very easily.
        final Annotations annotations = new Annotations(annotationClasses);

        synchronized (annotationCache) {
            final Map<Annotations, List<Method>> innerMap = annotationCache.get(clazz);
            if (innerMap != null) {
                final List<Method> methods = innerMap.get(annotations);
                if (methods != null) {
                    return methods;
                }
            }
        }

        // The methods to invoke have not been cached. Discover them via reflection.
        final List<Method> methods = discoverMethodsWithAnnotations(clazz, annotationClasses);

        // Store the discovered methods in our cache so that they are available next time.
        synchronized (annotationCache) {
            final Map<Annotations, List<Method>> innerMap = annotationCache.computeIfAbsent(clazz, key -> new ConcurrentHashMap<>());
            innerMap.putIfAbsent(annotations, methods);
        }

        return methods;
    }

    private static List<Method> discoverMethodsWithAnnotations(final Class<?> clazz, final Class<? extends Annotation>[] annotations) {
        // Consider two methods equal if they have the same name and same parameter types.
        final Comparator<Method> comparator = Comparator.comparing(Method::getName).thenComparing(new Comparator<Method>() {
            @Override
            public int compare(final Method o1, final Method o2) {
                return createString(o1.getParameterTypes()).compareTo(createString(o2.getParameterTypes()));
            }

            private String createString(final Class<?>[] parameters) {
                final StringBuilder sb = new StringBuilder();
                for (final Class<?> param : parameters) {
                    sb.append(param).append(",");
                }
                return sb.toString();
            }
        });

        // We want to de-dupe methods that are equal to one another based on our definition of equality (name & argument class types).
        final Set<Method> methods = new TreeSet<>(comparator);

        for (Method method : clazz.getMethods()) {
            if (isAnyAnnotationPresent(method, annotations)) {
                methods.add(method);
            }
        }

        // Look at all super classes recursively, adding to our list of methods if it has any that are not already present.
        // This way, if a class overrides a method in the superclass, the superclass's implementation won't be added. But any
        // method that exists in the superclass that isn't overridden will still be added.
        final Class<?> superClass = clazz.getSuperclass();
        if (superClass != Object.class) {
            final List<Method> superMethods = discoverMethodsWithAnnotations(superClass, annotations);
            methods.addAll(superMethods);
        }

        return new ArrayList<>(methods);
    }


    private static boolean isAnyAnnotationPresent(Method method, Class<? extends Annotation>[] annotations) {
        for (Class<? extends Annotation> annotation : annotations) {
            if (isAnnotationPresent(method, annotation)) {
                return true;
            }
        }
        return false;
    }

    private static boolean isAnnotationPresent(final Method method, final Class<? extends Annotation> annotationClass) {
        final Annotation annotation = method.getAnnotation(annotationClass);
        return annotation != null;
    }

    private static Object[] buildUpdatedArgumentsList(boolean quietly, Method method, Class<?>[] annotations, ComponentLog processLogger, Object... args) {
        boolean parametersCompatible = true;
        int argsCount = 0;

        Class<?>[] paramTypes = method.getParameterTypes();
        for (int i = 0; parametersCompatible && i < paramTypes.length && i < args.length; i++) {
            if (paramTypes[i].isAssignableFrom(args[i].getClass())) {
                argsCount++;
            } else {
                logErrorMessage("Can not invoke method '" + method + "' with provided arguments since argument " + i + " of type '" + paramTypes[i]
                        + "' is not assignable from provided value of type '" + args[i].getClass() + "'.", processLogger, null);

                if (quietly){
                    parametersCompatible = false;
                } else {
                    argsCount++;
                }
            }
        }

        Object[] updatedArguments = null;
        if (parametersCompatible) {
            updatedArguments = Arrays.copyOf(args, argsCount);
        }
        return updatedArguments;
    }

    private static void logErrorMessage(String message, ComponentLog processLogger, Throwable e) {
        if (processLogger != null) {
            if (e != null) {
                processLogger.error(message, e);
            } else {
                processLogger.error(message);
            }
        } else {
            if (e != null) {
                LOG.error(message, e);
            } else {
                LOG.error(message);
            }
        }
    }

    /**
     * Invokes all methods on the given instance that have been annotated with
     * the given preferredAnnotation and if no such method exists will invoke
     * all methods on the given instance that have been annotated with the given
     * alternateAnnotation, if any exists. If the signature of the method that
     * is defined in <code>instance</code> uses 1 or more parameters, those
     * parameters must be specified by the <code>args</code> parameter. However,
     * if more arguments are supplied by the <code>args</code> parameter than
     * needed, the extra arguments will be ignored.
     *
     * @param preferredAnnotation preferred
     * @param alternateAnnotation alternate
     * @param instance instance
     * @param logger the ComponentLog to use for logging any errors. If null, will
     *            use own logger, but that will not generate bulletins or easily
     *            tie to the Processor's log messages.
     * @param args args
     * @return <code>true</code> if all appropriate methods were invoked and
     *         returned without throwing an Exception, <code>false</code> if one
     *         of the methods threw an Exception or could not be invoked; if
     *         <code>false</code> is returned, an error will have been logged.
     */
    @SuppressWarnings("unchecked")
    public static boolean quietlyInvokeMethodsWithAnnotations(final Class<? extends Annotation> preferredAnnotation,
            final Class<? extends Annotation> alternateAnnotation, final Object instance, final ComponentLog logger,
            final Object... args) {
        Class<? extends Annotation>[] annotationArray = (Class<? extends Annotation>[]) (alternateAnnotation != null
                ? new Class<?>[] { preferredAnnotation, alternateAnnotation } : new Class<?>[] { preferredAnnotation });
        try {
            return invokeMethodsWithAnnotations(true, logger, instance, annotationArray, args);
        } catch (Exception e) {
            LOG.error("Failed while attempting to invoke methods with '" + Arrays.asList(annotationArray) + "' annotations", e);
            return false;
        }
    }

    private static class Annotations {
        private final Class<? extends Annotation>[] array;

        public Annotations(final Class<? extends Annotation>[] array) {
            this.array = array;
        }

        public Class<? extends Annotation>[] getArray() {
            return array;
        }

        @Override
        public int hashCode() {
            return Arrays.hashCode(array);
        }

        @Override
        public boolean equals(final Object other) {
            if (other == null) {
                return false;
            }
            if (other == this) {
                return true;
            }

            if (!(other instanceof Annotations)) {
                return false;
            }

            final Annotations otherAnnotations = (Annotations) other;
            return Arrays.equals(this.array, otherAnnotations.array);
        }
    }
}